I'm not sure I understand any of those methods of evaluating the value of a K&N filter.
The first thing that can't be debated is whether oil attracts dirt.
Anyone that doesn't believe that probably thinks they could walk a women through the center of a shopping mall without having to pry her out of every store in the place.
I believe that a properly oiled K&N could and should do a better job than a paper filter until it begins to get dirty. Oil attracts and collects dirt, and so the K&N will get dirty
much faster than the paper. It doesn't have a choice, no matter what skeptics insist to the contrary. I don't doubt that the paper material is more restrictive when they are both clean. The Hot Rod article pretty much bares that out.
This is from that K&N web site.
The service interval can be from 100 miles, such as a desert-racing vehicle, to 100,000 miles by a commercial semi truck. The proper way to determine when an air filter needs service is with an air restriction gauge.As the filter collects more and more dirt, the restriction value increases. At a predetermined point or rate of restriction, the filter is serviced. The maximum allowable of restriction for a K&N Filtercharger is 15" of vacuum (water). If the restriction is allowed to go higher, the filter media might become so restricted that the element could distort allowing dirty air to bypass the filter and enter the engine. Conversely, cleaning a filter too often will shorten its serviceable life expectancy.
If a filter is only being oiled once in 5 years and isn't getting dirty, then you must live in one hell of a clean dust-free area with never any wind or it just simply doesn't have enough oil on it. If you live in a agricultural area, it's clogging up right away and sucking dirt from around the sides like K&N says in the above quote.
My truck will stay with the oil bath and you'll never see me with a K&N on anything else.
